1. Field of the Invention
The present invention relates generally to a gas burner assembly, and more particularly relates to a burner assembly for burning natural gas or LP gas and which is adapted for use in a fireplace. Even more specifically, the present invention relates to a gas fireplace burner assembly which is capable of creating an essentially yellow flame pattern similar in appearance to yellow flames naturally formed in a real wood log fire with acceptable levels of carbon monoxide production.
2. Description of the Prior Art
Gas fireplace units have long been used as a substitute for real log or coal fires because of their convenience. The flames are produced by gas, either natural gas or liquid petroleum (LP) gas and the logs, while having the appearance and texture of real wood logs, are of a permanent non-combustible material.
The problem with all gas fireplace burner assemblies has been to produce a clean yellow flame. A clean blue flame is produced by mixing primary air with the gas before it is burned, thereby providing complete combustion and producing a clean flame. However, to make the flame yellow requires the elimination or reduction of the amount of primary air with only secondary air, air that mixes with the gas just at the base of the flame, to produce combustion. Examples of gas fireplace burners which are stated to produce a yellow flame are disclosed in U.S. Pat. No. 3,760,790 to Voges et al., U.S. Pat. No. 4,838,240 to Rieger, and U.S. Pat. No. 4,883,043 to Thow et al.
Many conventional gas fireplace units suffer from incomplete combustion. This may be due to insufficient secondary air, the uncontrolled direction of the secondary air in the burner or the flames impinging on the artificial logs used in the gas fireplace unit. The result is a yellow but very dirty flame producing carbon monoxide, soot and other forms of pollution, the soot collecting on the logs or other fuel substance on which the flames impinge.